Norwood scale
The standard classification of male pattern hair loss, stages I–VII, describing progressive recession and vertex thinning. Used to stage patients, plan grafts and communicate prognosis.
The Norwood scale (formally Hamilton–Norwood) is the standard staging system for male pattern hair loss, describing its typical progression in seven stages: from minimal temporal recession (I–II), through deepening frontal recession and vertex thinning (III–IV), to the bridging loss that merges front and crown (V–VI), and finally the horseshoe of residual donor hair (VII). It gives surgeons, researchers and patients a shared shorthand for “how far along” a pattern is.
Its clinical value is planning, not labelling. Stage informs graft arithmetic — how much area needs coverage now, what the donor can fund, and what future stages the plan must anticipate. A stage-III patient in his twenties with a strong family history is a different surgical decision from the same photograph at fifty, because the scale describes a moment in a progression, and surgery must be designed for where the pattern is going.
The scale has known limits. It maps the common male pattern, not every head: diffuse thinning without the classic front-to-back geography fits poorly, and female pattern loss follows a different distribution staged by the Ludwig scale instead. Staging is also a visual judgement — trichoscopy adds what the eye misses, quantifying miniaturisation in zones that still look covered.
Used well, Norwood staging disciplines conversation: it anchors consultation photographs, frames honest discussion of future loss and medical stabilisation, and exposes overpromising — a proposal to restore a juvenile hairline on an advanced stage with average donor density fails arithmetic the scale makes visible. It is a planning language, and clinics should document it in every surgical consultation.
Two refinements are worth knowing. The scale includes “A” variants describing predominantly front-to-back recession without a separate vertex patch — patterns that plan differently from the classic stages. And because the system is universal shorthand, it is also how research and industry surveys communicate case mix, which lets a clinic compare its own consultation population against published patterns rather than guessing what “typical” means.
